<?php
class Photo {
    public function open() {
        echo "打开投影机<br>";
    }
    public function change() {
        echo "将投影机输入切换dvd<br>";
    }
    public function setWidth() {
        echo "设置宽屏模式<br>";
    }
    public function close() {
        echo "关闭摄影机<br>";
    }
}